But sometimes the design work proves inadequate in practice -- on the train
railway, consider the now-notorious yaw damper failures on new UK trains
designed and built by Hitachi and by CAF; it turned out IIRC that the
frame members to which the yaw damper brackets are attached weren't strong
enough to resist the constantly varying forces from the dampers attached to
the bogies. The design engineers, under pressure to reduce material and
mass to the bare minimum, cut it too fine. Fatigue and materials science
in the practical world...

Hal Cain

On Mon, Sep 11, 2023 at 11:50 AMpeterm...@... < petermudie100@...> wrote:

> A computer model is only as good as the data fed into it. Garbage in

> Garbage out. The skill is in the engineer checking via other methods that

> the model is giving sensible results. Usually working it out from first

> principles.

>

> On Friday, 8 September 2023 at 16:56:59 UTC+10 Matthew Geier wrote:

>

>> Just proves that even with all modern computing tools at a

>> structural engineer's disposal, you will need to have some 'feel' for the

>> craft.

>>

>> Engineers are graduating from Uni these days with blind faith in computer

>> models. They are wizards at using CAD programs. However, they don't appear

>> to have any 'feel for the art'. And faced with their design failing in the

>> field they will argue that reality is wrong as the computer model said it

>> would work.

>> The engineering school I work for had this issue - they had a subject

>> where the students used CAD to design a simple pump. The twist was they

>> then got the mech workshop to make them. A significant number didn't

>> actually work. Apparently, the students complained about being marked down

>> when the physical item didn't work properly! The subject was primarily a

>> CAD subject, the pump build was intended to demonstrate the limitations of

>> computer models. Too many students just 'didn't get it'.

>>

>>

>>

>>

>> On Fri, 8 Sept 2023 at 08:42, Mal Rowe mal....@...> wrote:

>>

>>> On 08/09/2023 16:37, Matthew Geier wrote:

>>> > If they design for 20 years, you can expect expensive structural

>>> > augmentation will be needed at 20 years.

>>>

>>> Unless the designers worked for Siemens or CAF!

>>>

>>>

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